Don't take my word as an expert, I'm just trying to help.
Unfortunately, this is common in this kind of stores and it is not a problem of gg.deals, it is due to the way this kind of key selling marketplaces operates.
Probably someone has put a key for sale at that price (2.77), and at that moment gg.deals stored a snapshot, then the key was sold immediately but....
- It takes some time until the store withdraws the stock at that price.
- It takes some time until gg.deals syncs again to get the new lower price.
Regards